Method and apparatus for reducing ghost images with a tilted cholesteric liquid crystal panel

Abstract

A collimating apparatus that reduces ghost images in the field of view of a main image generated. The collimating apparatus includes a meniscus lens having a reflective concave surface; a cholesteric liquid crystal (CLC), aligned on an axis common with the meniscus lens, disposed on the concave side of the meniscus lens, positioned to reflect light onto the concave surface and having a tilt making the normal of the CLC different from the normal of the meniscus lens; and an image source, disposed on the convex side of the meniscus lens and having a tilt corresponding to the tilt of the CLC. The tilted pair of the meniscus and image source direct any ghost images produced by light leaking through the CLC away from the line of sight of an observer of the main image.

What is claimed is: 
     
       1. An optical collimating apparatus comprising: a meniscus lens having a reflective concave surface; and   a cholesteric liquid crystal (CLC), aligned on an axis common with said meniscus lens, disposed on said concave side of said meniscus lens, positioned to reflect light onto said concave surface and having a tilt making the normal of said CLC different from the normal of said meniscus lens; and   an image source, disposed on the convex side of said meniscus lens and having a tilt corresponding to said tilt of said CLC.   
     
     
       2. The optical collimating apparatus of claim 1 wherein said image source comprises an image source, disposed on both the convex side and the concave side of said meniscus lens.   
     
     
       3. The optical collimating apparatus of claim 2 wherein said CLC comprises a CLC having a tilt making the normal of said CLC more than zero (0) degrees and less than thirty (30) degrees different from the normal of said meniscus lens.   
     
     
       4. The optical collimating apparatus of claim 1 wherein said CLC comprises a CLC having a tilt making the normal of said CLC more than zero (0) degrees and less than thirty (30) degrees different from the normal of said meniscus lens.   
     
     
       5. An optical collimating apparatus comprising: a meniscus lens having a reflective concave surface; and   a cholesteric liquid crystal (CLC), aligned on an axis common with said meniscus lens, disposed on said concave side of said meniscus lens, positioned to reflect light onto said concave surface and having a tilt making the normal of said CLC more than zero (0) degrees and less than thirty (30) degrees different from the normal of said meniscus lens; and   an image source, having a tilt corresponding to said tilt of said CLC.   
     
     
       6. A method for directing a ghost image from a line of sight, said method comprising: disposing an image source on the convex side of a meniscus lens;   then collimating light from said image source by means of said meniscus lens towards a cholesteric liquid crystal (CLC);   tilting said CLC to direct any light leaking through said CLC from said line of sight and to reflect a portion of said collimated light back to the concave side of said meniscus lens and correspondingly tilting said image source;   then reflecting said portion of light from the concave side of said meniscus lens back to said CLC; and   then transmitting said reflected light through said CLC to said line of sight.   
     
     
       7. The method of claim 6 wherein said step of disposing comprises disposing said image source on both the convex and concave sides of said meniscus lens.   
     
     
       8. The method of claim 7 wherein said step of tilting comprises tilting said CLC at an angle greater than zero (0) degrees and less than thirty degrees (30) from a normal of said meniscus lens.   
     
     
       9. The method of claim 6 wherein said step of tilting comprises tilting said CLC at an angle greater than zero (0) degrees and less than thirty degrees (30) from a normal of said meniscus lens.   
     
     
       10. A method for directing a ghost image from a line of sight, said method comprising: collimating light from an image source by means of a meniscus lens towards a cholesteric liquid crystal (CLC);   tilting said CLC more than zero (0) degrees and less than thirty (30) degrees from the normal of said meniscus lens to direct any light leaking through said CLC from said line of sight and to reflect a portion of said collimated light back to the concave side of said meniscus lens and correspondingly tilting said image source;   then reflecting said portion of light from the concave side of said meniscus lens back to said CLC; and   then transmitting said reflected light through said CLC to said line of sight.